Heterogeneous photocatalysis applying TiO2 based catalysts has been widely studied for removing inorganic and organic compounds from water and for bacterial inactivation. This available and low-cost catalyst has demonstrated to be effective in the removal of organic pollutants and inactivation of pathogenic bacteria from water. The design of proper types of industrial-scale photoreactors has not been yet successfully implemented, probably due to the conceptual complexity of modeling this process in real wastewater. As a result, TiO2 based photocatalysis is still considered an effective but energetic-inefficient process. In this work, Escherichia coli (gram-positive) and Enterococcus sp (gram-negative) were selected for studying the kinetics of TiO2 photocatalysis. Since several approaches, such as fist-order kinetics, are not truly representative of the bacterial inactivation process, the experimental data were fitted to different mathematical models, such as Gompertz model, which has demonstrated to describe the process properly. Moreover, the effect of the main variables of the process in the inactivation kinetic constant of the Gompertz model has ben studied. More precisely, light intensity, water matrix, catalyst concentration and bacteria have been under study and their effect has been included in the kinetic equation. Finally, operational and construction parameters of a 20 m3/d annular photoreactor for bacterial inactivation has been successfully optimized applying the proposed kinetic model.

This work was funded by the grant TED2021-129267B-I00 funded by MCIN/AEI/ 10.13039/501100011033 and by the “European Union NextGenerationEU/PRTR. Samuel Moles thanks the grant Margarita Salas funded by the European Union-NextGenerationEU. Authors thank also the Regional Government of Aragón under the Research Groups Support Program (B43_23R: Agua y Salud Ambiental and T22_23R: Grupo de Procesos Termoquímicos).

This special issue is dedicated to honor the retirement of Prof. Santiago Esplugas at the University of Barcelona (UB, Spain), a key figure in the area of Catalytic Advanced Oxidation Processes.

Peer reviewed